Mosquito repellence induced by tarsal contact with hydrophobic liquids
Mosquito legs have a unique highly water-repellent surface structure. While being beneficial to mosquitoes, the water-repellence of the tarsi enhances the wettability of hydrophobic substances such as oils. This high wettability induces strong attraction forces on a mosquito’s legs (up to 87% of the mosquito’s weight) towards the oil. We studied the landing behaviour of mosquitoes on oil-coated surfaces and observed that the mosquito contact time was reduced compared to that on hydrophilic-liquid-coated surfaces, suggesting that the oil coating induces an escape response. The observed escape behaviour occurred consistently with several hydrophobic liquids, including silicone oil, which is used globally in personal care products. As the repellent effect is similar to multiple hydrophobic substances, it is likely to be mechanically stimulated owing to the physical properties of the hydrophobic liquids and not due to chemical interactions. On human skin, the contact time was sufficiently short to prevent mosquitoes from starting to blood-feed. The secretion of Hippopotamus amphibius, which has physical properties similar to those of low-viscosity silicone oil, also triggered an escape response, suggesting that it acts as a natural mosquito repellent. Our results are beneficial to develop new, safe, and effective mosquito-repellent technologies.
Contact angle of various liquids on the legs of mosquitoes.
Attractive force measurements.
Behaviours of mosquitoes landing on hydrophobic liquids.
Effect of PDMS viscosity and application ratio on contact time.
Effect of PDMS viscosity on attractive capillary forces.
Behaviours of mosquitoes landing on actual human skin.
Methods/ Data availability/ References
・題名（英文）：Mosquito repellence induced by tarsal contact with hydrophobic liquids
・著者：Hiroaki Iikura, Hiroyuki Takizawa, Satoshi Ozawa, Takao Nakagawa, Yoshiaki Matsui & Hiromi Nambu
(KAO Corporation, Material Science Research, and Personal Health Care Products Research)
・受付日：7 April 2020
・受理日：14 August 2020
・公開日：2 September 2020